This is the ultimate short-cut meal. It turns leftover veggie lasagna into a robust and satisfying soup with just a few added ingredients.
In a large skillet over medium heat, melt the butter together with the oil. Add the onions, and cook, stirring frequently, until browned, about 7 minutes.2.
Add the carrots and celery, and cook, stirring, until the vegetables are softened, and the flavors have melded, 8-10 minutes.3.
Add crushed tomatoes, tomato paste and water and bring to a boil. Reduce heat to simmer for 30 minutes.4.
Add leftover lasagna and fresh basil. Bring to a boil, then reduce the heat and simmer for about 10 more minutes. Dilute the soup with a touch more liquid, if needed.5.
Using a hand blender, blend the soup until smooth. Season to taste with salt and pepper.6.
To serve, ladle into warmed soup bowls or mugs, and top with a fresh basil leaf or two.